Magnetic storage systems are used to magnetically store information. In such a system, the direction of a magnetic field in a magnetic storage medium is altered to form a pattern representative of stored information.
There are two general techniques for magnetically recording information on a storage medium. One technique, known as “longitudinal” recording, has found widespread use. In longitudinal recording, the direction of the magnetic field in a plane of the storage medium is altered in a manner to store information. Another technique is known as “perpendicular” recording. In perpendicular recording, the magnetic field is impressed into the storage medium in a direction which is perpendicular to the plane of the medium. With the magnetic field direction perpendicular to the plane of the medium as opposed to parallel with the plane, information can be stored at higher density.
There has been an ongoing effort to increase the bit densities in magnetic recording. Bit density refers to the number of flux reversals (i.e. changes in the direction of a magnetic field) which can be written to the storage medium in a given area. The size of such a flux transition is related to the size and focus of a magnetic write field generated by a magnetic head. One traditional type of magnetic head is known as an inductive head which uses a current passed through a coil of wire. This causes a magnetic field to be generated across a gap formed between two pole tips.
There is also an ongoing effort to use magnetic storage medium which has a high coercivity. Such medium require stronger and more focused write field to impress a flux reversal. With the inductive head designs, it is difficult to obtain a tightly focused magnetic field with a sufficiently high field strength to write data perpendicularly to such a medium at ever increasing bit densities.
The present invention provides a solution to these and other problems and offers advantages over the prior art.